Deciding where your element points go do not matter if you will not use cards to boost your damage! Resists don't matter in pve.
50/50/50/50 is the same as 100/100/0/0 and that is also the same as 100/34/33/33. The final damage at the end will always be 500 pvp or whatever it is for pve (multiplier increases as you level up).
If you plan on using op max level cards this will be your pvp damage, pve has a different multiplier but pvp numbers look cleaner.
If using singles you should max your primary element and it won't matter what you put your points in after that since it will always be the same number.
100/34/33/33 or 100/100/0/0 is the same thing damage wise unless facing someone with resist. Max damage with just cards will be 2500 (8 single cards = 8 cards total)
If using duals you should max the 2 primary elements duals are made for, rest points you can evenly distribute them or stack them on 1 other element, same damage.
100/100/0/0 or 0/0/100/100 Max damage with just cards will be 3100 (6 dual+2 single cards=8 cards total)
If using 4 elemental attack your best bet is to max 1 element then evenly distribute because singles are better somehow. Remember you can only put singles in 2 ring slots.
100/34/33/33 the damage will be 2500 ( 6 4element + 2 singles = 8 Cards total)
If you evenly distribute it...
50/50/50/50 the damage will be 2250 ( 6 4element + 2 singles = 8 Cards total)
Basically the highest pve damage will be duals. Highest potential pvp damage will be duals against no resist.
So I recommend going 100/100/x/x .